In the five years since the first large-scale transit surveys began operating, over 100 gas-giant planets have been discovered in close orbits around their host stars. A sizeable minority among these so-called hot Jupiters are found to be in orbits that are strongly inclined or even retrograde with regard to the spin axes of their host stars. This surprising result suggests that migration in a protoplanetary disc may not be the only way to bring a Jupiter into a very close orbit. In this talk I will review the properties of the ensemble of transiting hot Jupiters, and examine the empirical evidence for the various planet-migration processes that may shape these systems.